Substrate treatment method for portion to be coated

ABSTRACT

A portion to be coated of a workpiece is subjected to substrate treatment by blasting to provide an anchor effect without leaving abrasive grains thereon. A substrate treatment method for a portion to be coated includes ejecting an elastic abrasive onto a portion to be coated of a workpiece to form irregularities with a predetermined surface roughness, thereby providing an anchor effect for a coating to be formed without causing the abrasive grains to be embedded in the surface of the workpiece. The elastic abrasive includes elastic carriers and abrasive grains, particularly, insulating abrasive grains, compounded and dispersed in the base material as an elastic body or carried on surfaces of the base materials by, for example, adhesion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to substrate treatment methods for a portion on which a coating is to be formed (referred to as a “portion to be coated” in the present invention) of an article to be treated, namely, a workpiece, and particularly to a substrate treatment method for a portion to be coated of a workpiece, such as a sliding part, by blasting before a coating is formed on the surface of the sliding part for various purposes, including increased hardness, reduced friction, improved corrosion resistance, improved high-temperature oxidation resistance, and decoration.

2. Description of the Prior Art

The term “blasting” used in the present invention refers to a wide variety of blasting methods by which an abrasive can be ejected onto a portion to be coated of a workpiece at a predetermined ejection speed and pressure. Examples of blasting methods include fluid blasting, such as dry blasting and wet blasting, in which the abrasive is ejected with a compressed fluid such as compressed air, centrifugal blasting (impeller blasting), in which the abrasive is ejected by applying a centrifugal force generated by rotating an impeller, and impact blasting, in which the abrasive is hit and ejected by an impact rotor.

In general, a coating of diamond-like carbon (DLC), TiAIN, TiN, or TiC, for example, is formed on a portion over which another member slides, such as a cutting edge of a cutting tool, for various purposes, including increased hardness, reduced friction, improved corrosion resistance, and improved high-temperature oxidation resistance.

When the coating is to be formed on the surface of the workpiece, the portion to be coated is roughened to a predetermined surface roughness so that the coating adheres firmly to the surface of the workpiece. This substrate treatment allows some of the coating to enter irregularities formed in the coated surface to provide namely “an anchor effect”, thus increasing the peeling strength (strength for scrape to peel off) of the coating and therefore its durability.

Examples of methods for roughening the portion to be coated to a predetermined surface roughness in the substrate treatment performed before the coating is formed include grinding, chemical etching, reactive ion etching, laser processing, and blasting.

Of these, blasting can be relatively easily performed simply by ejecting abrasive grains onto the portion to be coated. This method, in particular, has attracted attention because it allows substrate treatment to be carried out at relatively low cost.

When the portion to be coated of the workpiece is subjected to substrate treatment by blasting, the speed of the abrasive grains upon collision can reach, for example, 200 m/s or more.

The abrasive grains used are generally formed of a material harder than the workpiece so that the surface of the workpiece can be successfully treated, for example, cut. Use of such abrasive grains has been found to cause a phenomenon whereby, when the abrasive grains collide with the workpiece at high speed as described above, they stick into the surface of the workpiece and are then further embedded on the surface thereof and nearly the surface therein when succeeding abrasive grains collide with the stuck grains.

The embedding of the abrasive grains is particularly noticeable if the workpiece is formed of a malleable and ductile material with a relatively low hardness, such as aluminum, copper, brass, or zinc. In addition to such materials, the above phenomenon occurs for a variety of materials including metals, cemented carbide, which is a metal composite, semiconductors such as silicon, and engineering plastics, but excluding hard and brittle materials such as glass and ceramics.

The applicant has proposed a method for forming a glossy surface such as a mirror-finished surface by sand blasting, although this method is not intended for substrate treatment of a portion to be coated (see Japanese Unexamined Patent Application Publication No. 2005-22015 (Patent Document 1)). According to this method, abrasive grains are ejected together with a compressed fluid onto a surface of a workpiece at an incident angle θ such that the following condition is satisfied:

0<V·sin θ≦1/2·V

where V is the speed of the abrasive grains in an ejection direction and θ is the angle at which the abrasive grains are incident on the surface of the workpiece. This method produces a jet of abrasive grains along the surface of the workpiece.

As described above, when the substrate treatment for providing the anchor effect is performed by blasting to improve, for example, the peeling resistance of the coating, the blasting causes the abrasive grains to be embedded in the surface of the workpiece.

The embedded abrasive grains cause problems in a subsequent coating process.

For example, if the subsequent coating process is performed by vapor deposition such as physical vapor deposition (PVD) or chemical vapor deposition (CVD), no coating is formed in regions around protuberances formed by the embedded abrasive grains because these regions are shaded by the protuberances during film growth. This results in uneven film thickness and formation of thin portions.

Even if a coating with a uniform thickness can be formed on the surface of the workpiece, including the protuberances formed by the embedded abrasive grains, the coating will have protuberances corresponding to those formed on the underlying surface, that is, the surface of the workpiece.

Hence, if such a coating is formed on, for example, a sliding part of a cutting tool, chips collide with the thin portions or protuberances in the coating, thus damaging the coating. This impairs the function of the coating because, for example, the coating starts to be broken and delaminated from the damaged portions.

If the coating is formed by a method in which a voltage is applied to the workpiece, such as PVD or electroplating, and if the abrasive grains embedded on the surface of or in nearly the surface of the portion to be coated are formed of an insulating material such as carborundum, green carborundum, or alumina, difference in applied voltages is occurred between the sites where the abrasive grains are embedded and their vicinities. This results in formation of a coating with uneven thickness or, in some cases, even failure to form a coating at the sites where the abrasive grains are embedded. Thus, the embedded abrasive grains can cause various problems in the coating process.

According to the blasting method disclosed in Patent Document 1, the incident angle θ at which the abrasive grains are ejected onto the workpiece is set at a predetermined oblique angle to reduce a perpendicular force component exerted on the abrasive grains, thereby preventing the surface of the workpiece from becoming a satin finished surface. This method allows for a reduction in the force exerted in such a direction as to embed the abrasive grains in the surface of the workpiece.

The results of an experiment carried out by the inventor of the present invention, however, have revealed that the embedding of the abrasive grains in the surface of the workpiece cannot be prevented by setting the incident angle θ at which the abrasive grains are ejected at a predetermined oblique angle, as in the method described in Patent Document 1. Thus, the above problem due to the residual abrasive grains cannot be solved simply by applying the method described in Patent Document 1 to the substrate treatment of the portion to be coated.

It is also possible to remove the abrasive grains embedded in the surface of the workpiece during blasting by polishing the surface of the workpiece by a method other than blasting, or by chemically etching the surface of the workpiece, after the blasting has been completed. For such methods, however, it is difficult to remove only the outermost portion, having the abrasive grains embedded therein, while maintaining the surface unevenness formed in the workpiece by blasting, and it is extremely difficult to control the surface roughness of the portion to be coated of the final product so that it can provide the anchor effect.

In addition, the use of a method other than blasting to remove the embedded abrasive grains, as described above, inevitably increases the cost of the substrate treatment because, for example, it complicates the process and requires an additional processing apparatus.

Accordingly, an object of the present invention, which has been made to solve the above problems of the related art, is to provide a substrate treatment method for a portion to be coated, so that it can provide an anchor effect, by a relatively simple method, namely, blasting, without causing abrasive grains to be embedded in the portion to be coated despite employing blasting for the surface processing.

SUMMARY OF THE INVENTION

To achieve the above object, a substrate treatment method for a portion to be coated according to the present invention includes ejecting an elastic abrasive onto a portion to be coated of a workpiece to form irregularities with a predetermined surface roughness, thereby providing an anchor effect for a coating to be formed on the portion to be coated without causing the abrasive grains to be embedded on the portion to be coated. The elastic abrasive includes a base material as an elastic body and abrasive grains compounded and dispersed in the base material as an elastic body or carried on surfaces of the base material as an elastic body.

In the above substrate treatment method for a portion to be coated, the surface roughness of the portion to be coated may be controlled by changing the grain size of the abrasive grains. In addition to or instead of changing the grain size of the abrasive grains, the surface roughness of the portion to be coated may be controlled by changing conditions under which the elastic abrasive is ejected.

To avoid electrical problems in the case where the abrasive grains are insulating, preferably, the abrasive grains have an average grain size of 0.5 to 230 μm, the elastic abrasive has an average grain size of 10 to 2,000 μm, the average grain size being selected on the basis of that of the abrasive grains, and the elastic abrasive is ejected at an ejection pressure of 0.01 to 0.5 MPa, an ejection distance of 10 to 200 mm, and an incident angle of 30° to 75°.

In the present invention, the abrasive may contain a colorant or a fluorescent colorant, such as an inorganic pigment or an organic pigment. Examples of the colorant include titanium oxide, zinc oxide, carbon black, white carbon, silica, mica, aluminum powder, metal flakes, iron oxide, azo dye, anthraquinone dye, indigo dye, sulfur dye, and phthalocyanine dye. The abrasive may also contain a perfume or an antimicrobial agent.

The abrasive may be ejected by a direct-pressure method, for example, by direct pressure, gravity, suction, or blowing.

In electroplating, which is an example of a coating method, as described above, a metal dissolved in a solution in a plating bath is electrochemically deposited on the surface of a workpiece by dipping the workpiece in the bath and supplying electricity through electrodes; therefore, it cannot be applied to insulating workpieces. Accordingly, a coating cannot stably be formed on any portion where an insulator is present on the surface of the workpiece. Any coating thus formed will exhibit peeling.

Even if a coating can be formed on a portion where a minute insulator is present, depending on the conditions of the electric field applied to the vicinity thereof, the coating may be defective as an electroplated coating because the insulator swells, thus impairing the surface adhesion.

To prevent the abrasive grains of the elastic abrasive, containing such an insulating material, from being embedded on the portion to be coated, the following processing conditions are preferred.

The processing pressure preferably ranges from 0.01 to 0.5 MPa. A pressure of less than 0.01 MPa is unsuitable for industrial use because the abrasive will be ejected from a nozzle at low ejection speed, and accordingly the surface of the workpiece will be processed at low processing speed (cutting speed). If the media are ejected at a processing pressure above 0.5 MPa, they collide with the surface of the workpiece at high processing speed and therefore experience a high load that forces the abrasive grains to come off the media, thus decreasing the life of the media. In addition, the processing speed decreases as more abrasive grains come off. Furthermore, the abrasive grains that come off are circulated and ejected from the nozzle again, thus causing the problem of embedded abrasive grains described above. More preferably, the processing pressure ranges from 0.02 to 0.4 MPa.

The ejection distance preferably ranges from 10 to 200 mm. If the ejection distance falls less than 10 mm, the distance between the substrate and the ejection nozzle is so small that the point of ejection on the workpiece at which the media are ejected is locally processed, thus causing unevenness. If the ejection distance is above 200 mm, it is difficult to efficiently process a target processing site because the media are ejected from the nozzle over an extended area. Preferably, the ejection distance ranges from 50 to 150 mm.

A nozzle tip from which the abrasive is ejected may have any shape that is appropriate for the surface conditions of the workpiece, such as a circular, rectangular, polygonal, or elliptical shape. For a circular nozzle tip, the diameter may be 0.5 to 20 mm. If the diameter is less than 0.5 mm, the nozzle has low processing capability because of low ejection energy due to loss of kinetic energy inside a flow channel and loss of energy at a wall surface inside the nozzle.

The abrasive grains used preferably have an average grain size of 0.5 to 230 μm. The surface to be processed can be treated to a lower surface roughness as the average grain size of the abrasive grains is reduced, under the same ejection conditions, including the ejection pressure, the ejection distance, the incident angle, and the average grain size of the elastic abrasive. In addition, the average grain size of the abrasive grains must be determined so that they can be carried by the base material as an elastic body without coming off under the particular ejection conditions. Smaller abrasive grains have a larger surface area and adhere more firmly to the base material as an elastic body than larger abrasive grains. Hence, the minimum grain size should be 0.5 μm (#20,000). The maximum grain size, on the other hand, should be 230 μm. Any larger grain size results in low adhesion to the base material as an elastic body. Such abrasive grains can come off, thus failing to provide a desired surface state, depending on the ejection conditions. In addition, the abrasive grains that come off are circulated, ejected from the nozzle, and embedded in the workpiece. More preferably, the average grain size ranges from 0.5 μm (#20,000) to 140 μm (#90).

The average grain size of the elastic abrasive depends on the shape and surface roughness of the workpiece. When controlling the surface roughness at the bottom of a groove shape, it cannot be sufficiently processed using an elastic abrasive having an average grain size larger than the size of the groove. Multiple grains must be allowed to enter the groove to process its surface. Hence, the grain size of the abrasive must be one third or less the size of the groove. The minimum average grain size of the abrasive is therefore preferably 10 μm.

In treating the surface of a flat workpiece, an abrasive with a larger grain size is advantageous in terms of processing efficiency; the grain size can be up to 2,000 μm. Any larger grain size results in a lower processing efficiency because it can be assumed that the number of grains ejected per unit time is decreased. Preferably, the grain size ranges from 20 to 1,500 μm. The minimum and maximum grain sizes are 5 μm and 20 μm, respectively, for an average grain size of 10 μm, and are 1,800 μm and 2,200 μm, respectively, for an average grain size of 2,000 μm, as detailed in Table 2 below.

As described above, the substrate treatment method for a portion to be coated according to the present invention has the following significant benefits.

It is possible to treat the surface of the workpiece to a desired surface roughness by a relatively simple method, namely, blasting, while successfully preventing the abrasive grains from being embedded on the surface of the workpiece.

As a result, it is possible to improve the adhesion strength, for example, of the coating to be formed while successfully preventing problems such as uneven thickness due to embedding of the abrasive grains and coating defects caused when the coating is formed by a method involving application of a voltage, such as PVD or electroplating.

It is also possible to easily control the surface roughness of the irregularities formed on the portion to be coated by changing the grain size of the abrasive grains ejected and/or the ejection conditions.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and advantages of the invention will become apparent from the following detailed description of preferred embodiments thereof provided in connection with the accompanying drawings in which:

FIG. 1 is a diagram illustrating a force exerted on abrasive grains;

FIGS. 2A to 2D are electron micrographs of a sample of Example 1 (formed of SPCC): FIG. 2A is a scanning electron microscope (SEM) image; FIG. 2B is a carbon (C) energy dispersive X-ray spectroscope (EDX) image; FIG. 2C is an iron (Fe) EDX image; and FIG. 2D is a silicon (Si) EDX image;

FIGS. 3A to 3D are electron micrographs of a sample of Comparative Example 1 (formed of SPCC, neither treatment by the present invention nor ejecting only abrasive is made; hereinafter called “untreated”): FIG. 3A is an SEM image; FIG. 3B is an EDX image of silicon (Si); FIG. 3C is an EDX image of carbon (C); and FIG. 3D is an EDX image of iron (Fe);

FIGS. 4A to 4D are electron micrographs of a sample of Comparative Example 2 (formed of SPCC, θ=90°): FIG. 4A is an SEM image; FIG. 4B is an EDX image of carbon (C); FIG. 4C is an EDX image of silicon (Si); and FIG. 4D is an EDX image of iron (Fe);

FIGS. 5A to 5D are electron micrographs of a sample of Comparative Example 3 (the surface of the sample of Comparative Example 2 was polished): FIG. 5A is an SEM image; FIG. 5B is an EDX image of carbon (C); FIG. 5C is an EDX image silicon (Si); and FIG. 5D is an EDX image of iron (Fe);

FIGS. 6A to 6D are electron micrographs of a sample of Example 2 (formed of SKD11): FIG. 6A is an SEM image; FIG. 6B is an EDX image of carbon (C); FIG. 6C is an EDX image of silicon (Si); and FIG. 6D is an EDX image of iron (Fe);

FIGS. 7A to 7D are electron micrographs of a sample of Comparative Example 7 (formed of SKD11, θ=90°): FIG. 7A is an SEM image; FIG. 7B is an EDX image of carbon (C); FIG. 7C is an EDX image of silicon (Si); and FIG. 7D is an EDX image of iron (Fe);

FIGS. 8A to 8E are electron micrographs of a sample of Comparative Example 9 (formed of cemented carbide, 0=90°): FIG. 8A is an SEM image; FIG. 8B is an EDX image of carbon (C); FIG. 8C is an EDX image of oxygen (O); FIG. 8D is an EDX image of aluminum (Al); and FIG. 8E is an EDX image of tungsten (W); and

FIGS. 9A to 9G are electron micrographs of a sample of Comparative Example 10 (formed of SKD11 and coated with TiAlN): FIG. 9A is an SEM image; FIG. 9B is an EDX image of nitrogen (N); FIG. 9C is an EDX image of aluminum (Al); FIG. 9D is an EDX image of titanium (Ti); FIG. 9E is an EDX image of iron (Fe); FIG. 9F is an EDX image of carbon (C); and FIG. 9G is an EDX image of silicon (Si).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Next, embodiments of the present invention will be described.

Overview

A substrate treatment method for a portion to be coated according to the present invention includes ejecting an elastic abrasive onto a surface of a workpiece to form irregularities with a predetermined surface roughness, thereby providing an anchor effect for a coating to be formed without causing the abrasive grains to be embedded on the surface of the portion to be coated. The elastic abrasive includes base material as an elastic body and abrasive grains compounded and dispersed in the base material as an elastic body or carried on surfaces of the base material as an elastic body with, for example, an adhesive.

Workpiece

The substrate treatment method for the portion to be coated according to the present invention can be applied to any article which is to be coated and in which the abrasive grains can be embedded when they are directly ejected by blasting.

Articles formed of various materials can be used as the workpiece in the present invention, including relatively soft, malleable and ductile metals in which the abrasive grains can readily be embedded, such as aluminum, copper, brass, and zinc. It is also possible to use other metals, cemented carbide, which is a metal composite, semiconductors such as silicon, and engineering plastics.

Naturally, the present invention is not suitable for workpieces formed of hard, brittle materials such as ceramics and glass because an abrasive is not embedded in such workpieces in blasting.

Type of Coating to be Formed

The surface treatment method according to the present invention may be applied not only to a surface treatment performed before a coating is formed by CVD or PVD, but also to a surface treatment performed before a coating is formed by a method such as electroplating or thermal spraying. As another example, the substrate treatment method may be applied to a surface treatment performed before a resin coating is formed by a method such as coating, as in fluoropolymer coating. Thus, the application of the method according to the present invention is not limited to any particular coating method.

As for the material used to form the coating, the surface treatment method according to the present invention may be applied to a surface treatment performed before a hard coating is formed using, for example, DLC, TiC, TiCN, TiCrN, TiAIN, TiSiN, CrSiN, CrAlN, CrN, or CrVN, to a surface treatment performed before a coating of any metal is formed by electroplating or thermal spraying, or to a surface treatment performed before a resin coating such as a fluoropolymer coating mentioned above is formed. Thus, the method of the present invention is independent of the material of the coating to be formed and can be applied to a surface treatment performed before forming a coating of any material.

Elastic Abrasive

The elastic abrasive used in the present invention includes the base material as an elastic body and the abrasive grains, having grinding capability, compounded and dispersed in the base material as an elastic body or carried on the surfaces of the base material as an elastic body. When the abrasive collides with the surface to be processed, the elastic force of the carriers prevents formation of depressions corresponding to the shape of the elastic abrasive on the surface being processed and also successfully prevents the abrasive grains from being embedded therein. The elastic abrasive absorbs the impact upon collision, thus preventing the abrasive grains from being embedded. At the same time, the elastic abrasive cuts the surface of the portion to be coated at sites where the abrasive grains contained in the elastic abrasive directly contact the surface of the portion to be coated, thereby forming irregularities with a predetermined surface roughness.

In the region where the elastic abrasive of the present invention collides with the surface of the workpiece, the impact applied to the sites where the base materials collide with the surface of the workpiece is cancelled by the elastic force of the base materials, whereas the sites where the abrasive grains, dispersed in the base materials, collide with the surface of the workpiece are exposed to the cutting effect, for example, of the abrasive grains. Hence, the abrasive of the present invention, having a relatively large grain size on the whole which is advantageous in terms of, for example, handling, can be used to perform the same blasting process as could be performed by ejecting the abrasive grains dispersed in the base materials alone, without causing the abrasive grains to be embedded.

The grain size of the elastic abrasive is not particularly limited and may be changed according to, for example, the materials of the elastic abrasive and the workpiece to be processed and the purpose of processing. As an example, the grain size may be 3 to 0.02 mm. In particular, an elastic abrasive with a small grain size is effective for cutting or polishing of minute regions.

An elastic abrasive including fine abrasive grains with an average grain size of 1 μm (#8,000) or less has the advantage of effectively utilizing the abrasive grains because the density of the abrasive grains per unit surface area of the elastic abrasive can be increased by reducing the grain size of the elastic abrasive as well.

The elastic abrasive may contain a colorant, such as a dye or a pigment, allowing visual determination of the grain size etc. of the abrasive grains of the elastic abrasive. The elastic abrasive may also contain a fluorescent colorant, a perfume, or an antimicrobial agent.

Next, the base materials and the abrasive grains constituting the elastic abrasive, the mixing proportion thereof, and a method for producing the abrasive will be described.

Base Materials

The abrasive grains, being responsible for the grinding capability of the elastic abrasive of the present invention, are carried in the base materials or on the surfaces thereof. The base materials are formed of an elastic body to prevent the elastic abrasive from sticking into the portion to be coated, for example, when the elastic abrasive is ejected onto and collides with the portion to be coated. The base materials are formed by mixing a raw material polymer with various additives, as described below.

Raw Material Polymer

The raw material polymer, serving as the major ingredient, is mixed with various additives described below to form an elastic body such as a rubber or a thermoplastic elastomer. The raw material polymer used may be in solid form or in liquid form, such as a latex rubber or an emulsion. In terms of the properties of the raw material polymer, a viscoelastic polymer is preferable to reduce the impact resilience of the base materials and the abrasive including the base materials.

Examples of the rubber include natural rubbers and various synthetic rubbers such as isoprene rubber, styrene-butadiene rubber, butadiene rubber, acrylonitrile-butadiene rubber, chloroprene rubber, ethylene-propylene rubber, chlorosulfonated polyethylene, chlorinated polyethylene, urethane rubber, silicone rubber, epichlorohydrin rubber, and butyl rubber.

An example of the viscoelastic rubber is Norsorex (available from Elf Atochem, S. A., France), which is a norbornene polymer.

Examples of the thermoplastic elastomer include styrene block copolymer, chlorinated polyethylene elastomer, polyethylene elastomer, nitrile elastomer, fluoroelastomer, silicone elastomer, ester-halogen-based polymer alloy, olefinic elastomer, vinyl chloride elastomer, urethane elastomer, and polyamide elastomer.

Examples of the viscoelastic material, in particular, include polynorbornene (trade name: Norsorex), Sorbothane, silicone gel, which has a polysiloxane structure, and ethylene-acrylic elastomer. To attain viscoelasticity, for example, Norsorex may be used with an aromatic or naphthenic oil and carbon black, serving as a reinforcing material, added and compounded thereto.

Such raw material polymers, including rubbers and thermoplastic elastomers, may be used alone or as a mixture thereof (used in combination).

In addition, rubbers and thermoplastic elastomers recycled from reclaimed waste products or waste materials produced in manufacturing processes may be used.

Additives

The raw material polymer is mixed with various additives before being processed into the base material as an elastic body.

When a rubber is used as the raw material polymer, the rubber polymer is mixed with various additives, such as a vulcanizing agent for crosslinking rubber molecules, a vulcanization accelerator for promoting the crosslinking reaction of the vulcanizing agent, a plasticizer for plasticizing the rubber to facilitate the mixing and dispersion of the additives and to increase the ease of processing such as rolling or extrusion, an adhesion promoter for attaining the adhesiveness required for rubber manufacture to increase the ease of processing, a filler for use as an extender to decrease product costs and for improving the physical properties (e.g., mechanical properties such as tensile strength and impact resilience) of the rubber and the ease of processing, and various other additives that are generally used for rubber forming, such as a stabilizer and a dispersant.

Examples of the filler used to add the weight of the elastic abrasive include metals, ceramics, inorganic materials, organic materials and resins that have lower hardness than the abrasive grains. Such materials can be added to adjust the density of the elastic abrasive to a level appropriate for blasting. In addition, conductive materials such as carbon black and metal particles can be used to avoid electrostatic charging.

Although a rubber polymer is used as the raw material polymer in this embodiment, a thermoplastic elastomer may also be used, as described above. In this case, various additives generally used to form thermoplastic elastomers can be used.

Abrasive Grains

The abrasive grains, which deliver grinding capability through contact with the workpiece, play a major role in cutting the surface of the portion to be coated in this method to form irregularities with a predetermined surface roughness. The abrasive grains are dispersed in the base materials, formed of the raw material polymer and the additives, or are carried on the surfaces, formed in a predetermined shape, of the base materials with, for example, an adhesive.

The abrasive grains may be formed of any material that allows the abrasive grains to be dispersed in or carried on the base materials and that can be processed to a desired state by blasting, and various known materials can be used.

Table 1 below shows examples of materials that can be used as the abrasive grains.

TABLE 1 Resins Nylon, polycarbonate, polyethylene, polypropylene, polystyrene, vinylchloride, polymethyl methacrylate, polyacetal, and cellulose acetate Plant-based Corn core, seed shells of walnut, apricot, nut, or peach or the like, pulp, and cork Metals Oxides of the following metals: iron, aluminum, silicon, titanium, vanadium, chromium, manganese, cobalt, nickel, copper, zinc, gallium, germanium, zirconium, niobium, molybdenum, rhodium, palladium, silver, indium, tin, antimony, and tellurium Ceramics Glass, quartz, alundum, white alundum, carborundum, green carborundum, zircon, zirconia, garnet, emery, carbon boride, titanium boride, aluminum magnesium boride, and boron nitride Inorganic Calcium carbonate, calcium sulfate, calcium fluoride, barium sulfate, barium chloride, aluminum sulfate, aluminum hydroxide, strontium carbonate, strontium sulfate, strontium chloride, titanium oxide, basic magnesium carbonate, magnesium hydroxide, carbon, graphite, molybdenum sulfide, and tungsten sulfide

In terms of cuttability, the hardness of the abrasive grains used is preferably equivalent to or higher than that of the material of the portion to be coated, although the hardness of the abrasive grains does not necessarily have to be equivalent to or higher than that of the portion to be coated, depending on, for example, the type of material of the workpiece and the processing conditions.

The irregularities are formed on the portion to be coated by cutting so that they have a sufficient surface roughness to provide the anchor effect under the particular conditions, including the material and thickness of the coating to be formed and the method for forming the coating. The grain size of the abrasive grains can be selected based on the irregularities to be formed (surface roughness).

Also, the grain size of the abrasive grains is not particularly limited and may be selected according to, for example, the final grain size of the abrasive produced with the base materials. For example, the grain size may be #20 to #20,000 (930 to 0.5 μm). To form a coarser surface, abrasive grains with a larger grain size (smaller number) may be used.

The shape of the abrasive grains may be changed according to, for example, the material of the workpiece and the blasting conditions. A wide variety of shapes can be used, including spherical, polygonal, cylindrical, flat, and acicular shapes, and combinations thereof.

Compounding Ratio

The mixing proportion (content) of the abrasive grains in the elastic abrasive preferably ranges from 10% to 90% by weight based on 100% by weight of the elastic abrasive.

If the content of the abrasive grains in the elastic abrasive is 10% by weight or less based on 100% by weight of the elastic abrasive, the elastic abrasive has high impact resilience due to the base material as an elastic body and absorbs the impact upon collision to such an extent that the cutting capability of the abrasive grains mixed in the base materials is unsatisfactorily delivered. Another problem occurs that such an elastic abrasive has low cutting capability, and therefore low processing capability, because the abrasive grains are present on the surface of the elastic abrasive at an insufficient density.

If the content of the abrasive grains is more than 90% by weight, which is a dominant proportion, the abrasive has low adhesion between the abrasive grains and the base materials. When such an elastic abrasive is ejected onto and collides with the surface to be processed, its collision energy can noticeably crush the abrasive, and can also embed the abrasive grains of the crushed abrasive in the portion to be coated.

More preferably, the mixing proportion of the abrasive grains in the abrasive can be 60% to 90% by weight based on 100% by weight of the elastic abrasive. With such a mixing proportion, the elastic abrasive can be more successfully prevented from being crushed while its impact resilience and grinding capability are maintained.

In particular, dust explosion of a pulverized elastic abrasive can be prevented if it contains abrasive grains formed of a material that does not cause dust explosion in an amount of more than 70% by weight, even if the base materials are formed of a material that can cause dust explosion.

In addition, if the abrasive grains of the elastic abrasive are not only deposited on the surfaces of the base materials, but are also dispersed in the base materials, the elastic abrasive can maintain its grinding capability even if the abrasive grains present on the surfaces of the base materials of the elastic abrasive are, for example, removed, delaminated, crushed, or worn by various impacts and frictions occurring in a blasting process, including ejecting the abrasive onto the workpiece, polishing and cutting the surface to be processed, and recovering the elastic abrasive and sieving or dividing its flow path, because the impacts and frictions in the blasting process also wear and crush the base materials so that new abrasive grains appear on the surfaces of the base materials.

Accordingly, the abrasive of the present invention has superior durability, does not require the step of regenerating the elastic abrasive, can withstand extended and repeated use, and is highly suitable for use in abrasive-circulating processing lines. The new abrasive grains, as described above, can be made to appear successfully by adjusting, for example, the amount of wear of the base materials, the rate of crushing, and the brittleness of the abrasive. This can be achieved by changing, for example, the material of the base materials, the mixing proportion (content) of the abrasive grains in the elastic abrasive, and the production process.

Production Method

If the raw material polymer used is the rubber (raw material rubber) described above, the elastic abrasive of the present invention can be produced by a known rubber manufacturing process.

Rubber products are generally produced through four steps: a kneading step, a rolling/extruding step, a forming step, and a vulcanizing step. The method for producing the elastic abrasive of the present invention will now be described by following these four steps.

First, in the kneading step, the raw material rubber is subjected to mastication (in which a mechanical shear force is applied to the raw material rubber to, for example, break down aggregates of molecules and cleave their molecular chains, thereby adjusting the plasticity and fluidity of the rubber to those appropriate for mixing of the additives and forming) and is then subjected to compounding (in which the masticated raw material rubber is mixed with the additives with a mechanical shear force applied to plasticize the rubber and to disperse the additives in the rubber). In the present invention, the abrasive grains are compounded together with the additives, such as a vulcanizing agent and a filler, in the kneading step so that the resultant abrasive has the abrasive grains dispersed in the base materials.

The mastication and compounding in the kneading step may be performed using any known kneading machine, such as an internal mixer, as typified by a Banbury mixer, an open roll mill, a kneader, or a stirrer capable of kneading while using shear force.

Next, in the rolling/extruding step, the raw material prepared by kneading the raw material rubber together with the additives and the abrasive grains to an appropriate plasticity is processed into a shape that is formable in the subsequent forming step, such as a plate, sheet, or lump shape.

The apparatus used in this step may be, for example, a calender, which includes an array of rollers, or an extruder, which includes a screw.

The raw material processed into an appropriate shape in the rolling/extruding step, as described above, is formed into a predetermined size and shape in the forming step. To process the raw material with a shape such as a plate, sheet, or lump shape into fine grains for the production of the abrasive in the present invention, the raw material is crushed into pellets that are screened to a predetermined grain size. The crushing can be performed using any known crushing machine.

Subsequently, the grains prepared in the forming step are heated in the vulcanizing step, where the vulcanizing agent contained in the grains induces a crosslinking reaction to vulcanize the base materials, but not the abrasive grains, into an elastic body. In the vulcanizing step, any known apparatus such as a press, a vulcanizing pan, or a continuous extrusion vulcanizer may be used.

The grain formation (forming step) and the vulcanization by crosslinking (vulcanizing step) may be reversed in order. For example, the raw material processed into an appropriate shape in the rolling/extruding step may be directly transferred to the vulcanizing step and be vulcanized into an elastic body before being crushed into grains in the forming step.

If the raw material polymer used is a thermoplastic elastomer, the elastic abrasive can be produced by a known thermoplastic-elastomer manufacturing process. An abrasive with a desired grain size can be produced through a kneading step in which the raw material polymer is subjected to mastication and compounding with the additives and the abrasive grains, a forming step in which the kneaded raw material is melted by being heated above its melting point and is, for example, extruded or injected, and a crushing step in which the elastic body thus formed is crushed and screened to a predetermined grain size. In the kneading step, a roll mill, a pressure kneader, or an internal mixer, for example, may be used.

If the abrasive to be produced has the abrasive grains carried on the surfaces of the base materials, an adhesive, for example, may be used to deposit the abrasive grains on surfaces of base materials having no abrasive grains mixed or dispersed therein and formed into a predetermined shape.

Ejection Method

The abrasive may be ejected onto the surface of the workpiece together with a compressed fluid such as compressed air or, as described above, may be ejected by a centrifugal force from a rotating impeller or may be hit and ejected by an impact rotor. Thus, the ejection method used may be any method that allows the ejection of the abrasive under desired conditions.

In this embodiment, the abrasive is ejected by the ejection method using a compressed fluid, particularly, compressed air, because the ejection speed of the abrasive, for example, can be controlled relatively easily.

The abrasive is preferably ejected onto the portion to be coated at an acute incident angle (less than 90°), more preferably 60° or less, still more preferably 45° or less.

The incident angle of the abrasive is preferably oblique with respect to the workpiece because, as shown in FIG. 1, the force component, V·sin θ, exerted in such a direction as to embed the abrasive colliding with the surface of the workpiece in the surface of the workpiece is decreased with decreasing incident angle θ of the abrasive colliding with the surface of the workpiece. Hence, the abrasive grains carried on the base material as an elastic body can more reliably be prevented from being embedded in the surface of the workpiece under a synergistic effect provided by reducing the incident angle θ, as described above.

EXAMPLES

Next, the results of tests for comparison of workpieces subjected to substrate treatment by the method of the present invention, as well as those after coatings were formed thereon, with workpieces subjected to substrate treatment by a known blasting method, as well as those after coatings were formed thereon, will be shown.

Examination of Embedded Abrasive Grains

Next, the results of examination of embedded abrasive grains on workpieces formed of various materials and subjected to different substrate treatments, including samples subjected to substrate treatment by the method of the present invention, untreated samples, and samples subjected to substrate treatment by a typical blasting method, will be shown below.

Cold-Rolled Steel Sheet (SPCC) Treatment Test

Processing Conditions

Example

The substrate treatment method (Example) of the present invention was performed under the conditions shown in Table 2 below.

TABLE 2 Processing Conditions for Substrate Treatment under the present Invention (Example 1-4) Example 1 Example 2 Example 3 Example 4 Workpiece Cold-Rolled Alloy Tool Steel Cemented Carbide Aluminum Steel Sheet (SKD11) (KHO3) manufactured by (A1100) (SPCC) Sumitomo Electric Industries, Ltd. Blasting “FDQ-SR” “SG-SR” “SG-SR” “LDQ-SR” Machine Fuji Mfng. Ejection Method Direct-pressure Gravity Gravity Direct-pressure (Blower) Compressed air Compressor Compressor Compressor Blower Supply method Condition Of Ejection Pressure (MPa)    0.3   0.2    0.5    0.02 Ejection  70 50 100 50 distance(mm) Incident angle θ°  30 45  60 75 Nozzle-tip  8 10  6 10 diameter(mm) Ejection material Abrasive grains compounded and dispersed in the base material Elastic abrasive Average 650 35 350 1000  grain size Minimum (μm) 500 20 200 800  Maximum (μm) 800 50 500 1200  Base material Rubber Abrasive grains “Fujilundum GC” “Fujilundum GC” “Fujilundum WA” “Fujilundum GC” Fuji Mfng. (green carborundum) (green carborundum) (white alundum) (green arborundum) Mesh #1000  #320  #320  #10000   Average size (μm)  (12) (40)  (40)  (1)

Comparative Examples

As Comparative Examples, blasting was performed using abrasive grains alone under the conditions shown in Table 3 below.

TABLE 3 Blasting conditions for Comparative Example 1 Blasting Machine “SGF-4” manufactured by Fuji Mfng. Gun “F2-4 type” nozzle-tip diameter of 8 mm Condition Of Ejection Pressure of 0.3 Mpa Incident angle θ° Ejection distance of 70 mm, 90° (Comparative Example 2) 45° (Comparative Example 2) 30° (Comparative Example 5) Ejection material “Fujilundum GC” manufactured by Fuji Mfng. (Green Carborundum), #1000 (average grain size of 12 μm) only Processing Method Manual Comparative Example 3 Sample of Comparative Example 2 whose surface is cut Comparative Example 6 Untreated SKD11 Steel Comparative Example 7 Blasting of Comparative Example 1 against SKD11 steel Comparative Example 8 Untreated Cemented Carbide (“KH03” manufactured by Sumitomo Electric Industries, Ltd.) Comparative Example 9 Blasting of Comparative Example 1 to the Cemented Carbide of Comparative Example 8 Comparative Example 10 Processing GC abrasives of #320 by the method of Comparative Example 1 at an incident angle of θ 90°

Test Method

The surfaces of the workpieces subjected to blasting under the processing conditions shown in Table 2 were exposed to a blast compressed air to remove deposits and were dipped in isopropyl alcohol (IPA) and subjected to ultrasonic cleaning for ten (10) minutes. The surfaces of the individual samples were examined by electron microscopy and X-ray spectroscopy.

The surface examination by electron microscopy was performed using the scanning electron microscope (SEM) “S-3400N” (manufactured by Hitachi, Ltd.). The X-ray spectroscopy was performed by energy dispersive X-ray spectroscopy (EDX; using INCA Energy 7021 manufactured by Oxford Instruments), in which the samples were irradiated with an electron beam, various X-rays generated from the samples were detected, its spectrum was displayed after segmentation using a pulse-height analyzer, and elements were identified and quantified from the spectrum.

The SEM and the EDX were both performed with an acceleration voltage of 15 eV. In the EDX, element analysis was performed on the surfaces of the samples by element mapping to identify the materials present thereon.

To examine the presence of green carborundum (GC) abrasive grains (formed of SiC), three elements, namely, iron (Fe), which is a constituent element of the workpiece material (SPCC), and silicon (Si) and carbon (C), which are constituent elements of GC (SiC), were selected for element identification.

Test Results

The workpiece used was a cold-rolled steel sheet (SPCC) having a size of 100×100 mm and a thickness of 3 mm. Samples were prepared by blasting the surface of the workpiece with the elastic abrasive (Example 1; see Table 2), without treatment (Comparative Example 1), by blasting the surface of the workpiece with abrasive grains at an incident angle θ of 90° (Comparative Example 2), 45° (Comparative Example 4), or 30° (Comparative Example 5) (see Table 3), and by cutting the surface of the sample prepared in Comparative Example 2 (θ=90°) (Comparative Example 3).

FIGS. 2A to 2D show an SEM image and EDX mapping images of the sample of Example 1. FIGS. 3A to 3D, 4A to 4D, and 5A to 5D show SEM images and EDX mapping images of the samples of Comparative Examples 1 to 3, respectively.

Table 4 shows the correspondences between the samples and FIGS. 2A to 2D, 3A to 3D, 4A to 4D, and 5A to 5D.

TABLE 4 Relation between each samples and drawings Corresponding Sample Name Processing Conditions Drawings Example 1 Blasting by elastic abrasives FIG. 2 Comparative Example 1 Untreated article FIG. 3 Comparative Example 2 Blasting by abrasive grains FIG. 4 (θ = 90°) Comparative Example 3 Abrading the surface of FIG. 5 Comparative Example 2

According to the EDX images (element mapping images) of Example 1, as shown in FIGS. 2B to 2D, iron (Fe), silicon (Si), and carbon (C) were all uniformly distributed over the surface of the sample of Example 1, and no localized distribution of silicon (Si) or carbon (C) was found.

FIGS. 3B to 3D show the EDX images of the untreated SPCC of Comparative Example 1. According to these images, iron (Fe), silicon (Si), and carbon (C) were all uniformly distributed.

These results demonstrate that the uniform distribution of silicon (Si) in the EDX image of Example 1 was due to the silicon (Si) inherent in the workpiece, namely, SPCC. This confirms that the abrasive grains compounded and dispersed in the elastic abrasive were not embedded in the surface of the workpiece, namely, SPCC, for the sample of Example 1, in which no localized distribution of silicon (Si) or carbon (C) was found.

Of the samples of the Comparative Examples, which were directly blasted with the GC abrasive grains (#1,000), the sample of Comparative Example 2, in which the incident angle θ was 90°, had a localized distribution of silicon (Si), as shown in FIG. 4C (circled regions). According to the iron (Fe) EDX image (see FIG. 4D), however, no localization of iron (Fe) was found at sites (circled regions) corresponding to the localized silicon (Si).

According to the results, the material of the abrasive grains, namely, SiC, remained on the processed surface of the sample of Comparative Example 2 after the cleaning using a blast of compressed air and the ultrasonic cleaning following the ejection of the abrasive grains. This demonstrates that the abrasive grains were embedded. Carbon (C) was nearly uniformly distributed because it was also contained in the treated steel (SPCC).

FIGS. 5A to 5D show the SEM and EDX images of the sample of Comparative Example 3, in which the surface of the sample of Comparative Example 2 was polished using diamond abrasive grains (#10,000; grain size: 1 μm).

As shown in FIGS. 5A to 5D, the abrasive grains, namely, SiC, embedded in the surface of the sample, were exposed by polishing the surface Comparative Example 2. This demonstrates that the abrasive grains were embedded in the surface of the workpiece when they were directly ejected.

The surface polishing with the diamond abrasive grains was performed using the blasting apparatus “LDQSR-3”, manufactured by Fuji Manufacturing Co., Ltd., at an ejection pressure of 0.06 MPa and a nozzle-tip diameter of 10 mm.

According to the EDX results, the silicon (Si) concentrations of the samples of Example 1, Comparative Example 1 (untreated SPCC), and Comparative Example 2 were 0.29 atomic percent, 0.31 atomic percent, and 7.5 atomic percent, respectively. These results, in terms of atomic percent, demonstrate that the sample of Example 1 had no abrasive grains embedded.

According to the SEM and EDX images (not shown) of the samples blasted with the adhesive grains at incident angles θ of 45° (Comparative Example 4) and 30° (Comparative Example 5), the material of the abrasive grains, namely, SiC, was found to be present, indicating that the abrasive was embedded. Thus, the embedding of the abrasive could not be prevented simply by adjusting the incident angle θ of the abrasive grains with respect to the workpiece.

Alloy Tool Steel (SKD II) Treatment Test

Processing Conditions and Test Method

A sample (Example 2) formed of alloy tool steel (SKD11) and subjected to substrate treatment by the method of the present invention, untreated SKD11 (Comparative Example 6), and a sample (Comparative Example 7) formed of SKD11 and subjected to blasting by ejecting abrasive grains were examined for abrasive grains embedded in the surfaces of the samples.

The processing conditions of Example 2 were as shown in Table 2, and the test method of Example 2 and the processing conditions and the test method of Comparative Example 7 were identical to those of Example 1 and Comparative Example 2, respectively, except that the workpiece was formed of a different material.

Test Results

According to the EDX results, the silicon (Si) concentration (%) of the sample of Comparative Example 7, in which the treatment was performed by ejecting abrasive grains, was 11.8 atomic percent, whereas those of Example 2, in which the substrate treatment was performed by the method of the present invention, and Comparative Example 6, in which no treatment was performed, were both 0.6 atomic percent.

Thus, the silicon (Si) concentration (%) of the sample of Example 2 was similar to that of the untreated sample (Comparative Example 6). This measurement of silicon (Si) concentration demonstrates that the GC abrasive grains (formed of SiC) were not embedded.

Also, from an SEM image of Example 2 shown in FIG. 6A and EDX images shown in FIGS. 6B to 6D, the silicon (Si) distribution was a similar map to those in EDX images (not shown) of the untreated SKD11 (Comparative Example 6).

These results demonstrate that no abrasive grains were embedded in the surface of the sample of Example 2, which was a condition resembling the surface of the untreated SKD11 (Comparative Example 6).

According to an SEM image shown in FIG. 7A and EDX images shown in FIG. 7B to 7D, on the other hand, silicon (Si) was localized on the surface of the sample of Comparative Example 7, in which the abrasive grains were ejected. This demonstrates that the ejected abrasive grains were embedded in the surface of the workpiece, namely, SKD11.

Treatment Test for Cemented Carbide (“KH03” manufactured by Sumitomo Electric Industries, Ltd.)

Processing Conditions and Test Method

A sample (Example 3) formed of a cemented carbide (“KH03” manufactured by Sumitomo Electric Industries, Ltd.) and subjected to substrate treatment by the method of the present invention, an untreated cemented carbide (Comparative Example 8), and a sample (Comparative Example 9) formed of the cemented carbide and subjected to blasting by ejecting abrasive grains were examined for abrasive grains embedded in the surfaces of the samples.

The processing conditions and the test method of Example 3 were as shown in Table 2.

The processing conditions and the test method of Comparative Example 9 were identical to those of Comparative Example 2 except that the workpiece was formed of a different material and that the abrasive grains ejected were Fujilundum WA #320 (formed of white alundum; manufactured by Fuji Manufacturing Co., Ltd.).

Test Results

FIGS. 8A to 8E show SEM and EDX images of the sample of Comparative Example 9, in which the abrasive grains formed of white alundum (formed of Al₂O₃) were ejected onto the cemented carbide, namely, tungsten carbide (WC).

As shown in FIGS. 8A to 8E, element mapping of aluminum (Al) and oxygen (O), which are constituent elements of the material of the abrasive grains, namely, aluminum oxide (Al₂O₃), gave EDX images corresponding to its SEM image. This demonstrates that the abrasive grains remained on the surface.

The surface of the sample of Comparative Example 9 was slightly polished using an elastic abrasive including base material as an elastic body and diamond abrasive grains (#10,000) compounded and dispersed therein. This revealed that the abrasive grains were embedded in the surface of the treated cemented carbide.

For the sample of Example 3, in which the cemented carbide was subjected to the substrate treatment by the method of the present invention, no embedded abrasive grains were found in SEM and EDX images (not shown).

Coating Test

As a coating test, a TiAIN coating, which is a hard coating, was formed on a workpiece formed of SKD11 by a plasma process.

A sample of Example 2 was prepared by blasting the substrate, formed of SKD11, with an elastic abrasive including base material as an elastic body and Green Carborundum (GC) abrasive grains (#320) compounded and dispersed therein under the conditions shown in Table 2 before forming the coating.

A sample of Comparative Example 10 was prepared by directly ejecting Green Carborundum (GC) abrasive grains (#320) onto the surface of the workpiece at an incident angle θ of 90° before forming the coating. The ejection conditions were as shown in Table 3.

After the TiAIN coatings were formed on the surfaces of the samples, the surfaces were treated by slightly polishing them using an elastic abrasive including base material as an elastic body and diamond abrasive grains (#10,000) compounded and dispersed therein to, for example, remove droplets on the coatings.

The samples of Example 2 thus prepared were examined for surface conditions and element distribution based on SEM and EDX images. According to the EDX images (not shown), only titanium, aluminum, and nitrogen were detected on the surface of the coating formed on the sample of Example 4. This demonstrates that a uniform TiAIN coating was formed on the surface.

According to the EDX images shown in FIGS. 9B to 9G, on the other hand, silicon (Si), which is a component of the abrasive, was strongly detected on the coating formed on the sample of Comparative Example 10, in which the substrate treatment was performed by directly ejecting the abrasive grains (see the circled region in FIG. 9G).

In the region where silicon (Si) was strongly detected, titanium, aluminum, and nitrogen, which are constituent elements of the coating, were detected in decreased amounts (see FIGS. 9B to 9D). This demonstrates that no coating was formed in the region where silicon (Si), which is a component of the abrasive grains, was detected, that is, a region where an abrasive grain was embedded by blasting.

The region where little coating was formed occurred because the Green Carborundum (GC) abrasive grains (formed of SiC), which are insulating, were embedded in the substrate and caused a different voltage to be applied compared with other regions.

Also, the SEM image confirms that little TiAIN coating was formed in the region where silicon (Si) was strongly detected.

The above results demonstrate that the substrate treatment based on the method of the present invention, in which the base material as an elastic body having the abrasive grains compounded and dispersed therein are ejected onto a workpiece, is more effective in forming a uniform coating than a substrate treatment based on a known blasting method in which abrasive grains are directly ejected onto a workpiece.

Friction Test

The samples thus prepared, namely, the sample of Example 2, in which the TiAlN coating was formed on the surface of the substrate formed of SKD11, and the sample of Comparative Example 10, were subjected to a friction test to compare the two samples for durability.

This friction test was a ball-on-disk test (the apparatus used was manufactured by Rhesca Co., Ltd.), in which friction was caused against a ball-shaped test piece, namely, a stainless steel (SUS304) ball having a diameter of 3/16 inches.

Before the test was started, the samples and the ball against which friction was caused were dipped in acetone and were subjected to ultrasonic cleaning to remove contaminants.

According to the results of the above friction test, the duration for which the friction coefficient of the sample of Example 2 remained stable was measured to be 20, with that of the sample of Comparative Example 10 being 1 (Comparative Example 10: Example 2=1:20), that is, 20 times the duration for which the friction coefficient of the sample of Comparative Example 10 remained stable.

The coating formed on the sample of Example 4 was found to remain stably laminated after the friction test and showed excellent results for coating adhesion strength, whereas the coating formed on the sample of Comparative Example 10 was found to be delaminated and could no longer be used as a coating.

Thus the broadest claims that follow are not directed to a machine that is configure in a specific way. Instead, said broadest claims are intended to protect the heart or essence of this breakthrough invention. This invention is clearly new and useful. Moreover, it was not obvious to those of ordinary skill in the art at the time it was made, in view of the prior art when considered as a whole.

Moreover, in view of the revolutionary nature of this invention, it is clearly a pioneering invention. As such, the claims that follow are entitled to very broad interpretation so as to protect the heart of this invention, as a matter of law.

It will thus be seen that the objects set forth above, and those made apparent from the fore going description, are efficiently attained and since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matters contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

Now that the invention has been described; 

1. A substrate treatment method for a portion to be coated, the method comprising; ejecting an elastic abrasive onto a portion to be coated of a workpiece to form irregularities with a predetermined surface roughness, thereby providing an anchor effect for a coating to be formed on the portion to be coated without causing the abrasive grains to be embedded in the portion to be coated, the elastic abrasive including base material as an elastic body and abrasive grains compounded and dispersed in the base material as an elastic body or carried on surfaces of the base material as an elastic body.
 2. The substrate treatment method for a portion to be coated according to claim 1, wherein; the surface roughness of the portion to be coated is controlled by changing the grain size of the abrasive grains in the elastic abrasive.
 3. The substrate treatment method for a portion to be coated according to claim 1, wherein; the surface roughness of the portion to be coated is controlled by changing conditions under which the elastic abrasive is ejected.
 4. The substrate treatment method for a portion to be coated according to claim 1, wherein; the abrasive grains are insulating and have an average grain size of 0.5 to 230 μm; the elastic abrasive has an average grain size of 10 to 2,000 μm, the average grain size being selected on the basis of that of the abrasive grains; and the elastic abrasive is ejected at an ejection pressure of 0.01 to 0.5 MPa, an ejection distance of 10 to 200 mm, and an incident angle of 30° to 75°.
 5. The substrate treatment method for a portion to be coated according to claim 1, wherein; there is no increase in an atom percent of silicon (Si) in the elastic abrasive.
 6. The substrate treatment method for a portion to be coated according to claim 1, wherein; the coating is formed by a method in which a voltage is applied to the workpiece excluding hard and brittle materials, and the abrasive grains are formed of an insulating material such as carborundum, green carborundum, or alumina.
 7. The substrate treatment method for a portion to be coated according to claim 4, wherein; the abrasive grains are insulating and have an average grain size of 1.0 to 40 μm and the abrasive grains are mixed and dispersed in the elastic abrasive made of rubber has an average grain size of 35 to 1,000 μm, the average grain size being selected on the basis of that of the abrasive grains; and the elastic abrasive is ejected at an ejection pressure of 0.02 to 0.5 MPa, an ejection distance of 50 to 100 mm. 